The problem is, I think, that inks based on a suitable solvent just aren't
likely to be very good for inkjet mechanisms. The bubblejets work by
thermally vaporizing a small bit of ink (sensitive to the solvent), and I'd
think that anything but the most exotic solvents would be prone to drying
up in the printheads on other types of inkjets (well, even on the
bubblejets.) For most inkjets, the absorption of the paper is an important
factor in the printing process (thus the need for special paper, special
CDs for CD printers, special transparencies, etc.)

Another option might be to buy a cheap hobbyist CNC machine and
change the routing tools to Draughtmans Ink pens.

Are cheap CNC machines cheaper than used pen plotters? Once you get a CNC
machine, you might as well have it mill away copper (aside from the rather
obnoxious cost of milling tools.) There's been a fair amount of traffic on
usenet in the past on which inks to use in plotter pens.

I have an LPKF PCB milling machine purchased off of ebay. It's quite
different to have turnaround time of a hour or two (for small PCBs) from
Eagle layout to solderable PCB. Sorta like having a word processor instead
of a typewriter; it's so easy to tweak things "just a little bit" that you
have trouble figuring out when you ought to be DONE.

(Hmm. I wonder if I can address that "obnoxious cost of milling tools"
issue by having the LPKF mill away (softer) resist coating, and then etching
to do the actual copper removal?)

IMO, there's a lot of work to be done with laser printers that would be more
promising than ink jets. To start with you can get rid of the power to that
fuser so that you're left with paper coated with loose toner powder; ought
to be easier to transfer to copper that way. Then there are assorted things
other than paper that might be interesting to run through the machine,
assuming that it's JUST for PCB use...

(The person who gave me the board said the machine was owned by a local
electronics college at the time he had access to use it, so they can't
be super-expensive, but I'm sure they're not cheap...)

There are two major companies I know of that make CNC PCB routers. T-tech
(http://www.t-tech.com)and LPKF (http://www.lpkf.com) I've seen others at trade shows, but
they haven't been around as long, and don't have the exposure or reputation.
Entry-level models run about $10k, plus another couple $k for necessary
vacuum system, tooling, and so on. Used models are available for cheaper,
sometimes. There's an LPKF machine on eBay right now at an current price
of $4.5k (and it's one of the larger models.) And you need a computer to
drive it (uses a serial port.)

I've been using an LPKF, bought from eBay, for maybe 6 months now, and have
run off perhaps a dozen small boards. (very small boards. In fact, that's
my motivation for getting the machine. Start designing 4x6 inch boards and
those prototype shops start to look pretty attractive at ~$50 each. Design
a 0.75x2 inch board that might not work, and you're still looking at $50 for
way too many of them from conventional shops...)

The way these things are built leads me to believe that it would be
relatively difficult to convert a standard plotter or CNC machine to do
similar tasks. They're SOLID, and the motors needed to move a router bit
removing metal at substantial speed and 0.01mm accuracy are pretty hefty.

Software wise, they look like HPGL plotters.

Eagle (and presumably other CAD packages) will generate "outline" data for
tracks (also in HPGL format, if you want), so in theory you don't need much
additional software. In reality, both plotters come with substantial
software that adds a lot of capability (multiple layers, milling, board
placement and multiplication, "rubout" functionality to remove extra copper,
tool and motor management, and more.) They charge a lot for the software,
and it's probably worth it (although the LPKF software can be agonizingly
slow, compared to the Eagle outline functions, for instance.)

There's a reason that you usually only see the bare minimum of copper routed
away. The tooling (carbide bits) that these things use doesn't last that
long, and standard pricing is quite high (~$17 milling bits. Each.) There
aren't a lot of second sources, either (unlike drill bits.) Grr.

There's a registration system that allows double-side board to be routed,
but holes are not plated through, of course, which I'm finding has nasty
effects on the way you might lay out a board. Single-sided circuit boards
work better, but single sided material seems to be relatively hard to find,
and if you have double-sided material you have to route both sides even if
your board is only single sided.

They're very noisy. Especially the vacuum cleaner.

I don't think I wasted my money, but it's also not quite as wonderful as I
thought it might be. By the time I use up the tooling that came with my
machine, I may be ready to re-think whether it makes more sense to use the
board-houses. (Of course, but then I also expect to have a bit more faith
that my PCBs will work...)

>The tooling (carbide bits) that these things use doesn't
>last that long, and standard pricing is quite high (~$17
>milling bits. Each.) There aren't a lot of second sources,
>either (unlike drill bits.) Grr.

How are the tip of the bits shaped? If they are flat like a normal milling
bit then this may be difficult, but if they are V shaped like a countersink
bit I would be tempted to try a normal carbide tipped drill as a bit if a
fine enough one was available. It may be necessary to grind the tip to a
sharp point, but you may get away with it for a quick development board
without doing this or using an expensive tip.

The tips are, usually, V shaped, at 30, 60 or 90 degree.
You can adjust the isolation width by milling depth.
The RF tips are 'like a normal' end-mills.
One can use phenolic paper PCB to reduce bit's wear.

Is there any way to return to 'Printer to PCB' or to switch to 'Toner to PCB'?

When using Dremel or other flex, take care about the XY tolerances and
repeatability!!

If interested, I can give you simple instructions to modify a Lexmark Z31
to accept a 1.5mm PCB.
Any good, practical, idea of FeCl resist ink in a printer cartridge?
Cristian

>How are the tip of the bits shaped? If they are flat like a normal milling
>bit then this may be difficult, but if they are V shaped like a countersink
>bit I would be tempted to try a normal carbide tipped drill as a bit if a
>fine enough one was available. It may be necessary to grind the tip to a
>sharp point, but you may get away with it for a quick development board
>without doing this or using an expensive tip.

>Well, I know I'd be interested. Perhaps you can setup a page on
>piclist.com about this?
>
>Josh
>--
>A common mistake that people make when trying to design something
>completely foolproof is to underestimate the ingenuity of complete
>fools.
> -Douglas Adams
>
>Cristian wrote:
>> If interested, I can give you simple instructions to modify a Lexmark Z31
>> to accept a 1.5mm PCB.
>> Any good, practical, idea of FeCl resist ink in a printer cartridge?
>> Cristian

Theres a company in the UK called Eurobearings (I used to work for them) who
sell all the stuff to make 3 axis milling/routing machines. They used to
have one that they'd built which was the size of a small room. You could put
a full size router onto it or a felt tip.

Mad bit of kit - might be worth ringing them to see if they still do all the
parts if anyone wants to build their own 3 axis machine

Point taken, I didn't consider that. Of course, it would still be easier
to dispose of than etchant. Unless you just pour it down the drain :)

You should look into re-usable etchant. I got the CuCl etchant described
here: http://www.dnai.com/~rexa/Projects/CuCl_ech.html to disolve copper
just fine, although I don't know how compatible it is with typical hobbyist
(or professional) resists (ie I etched away a whole side worth of copper,
but didn't try to do a real PCB.)

*>>The tooling (carbide bits) that these things use doesn't
*>>last that long, and standard pricing is quite high (~$17
*>>milling bits. Each.) There aren't a lot of second sources,
*>>either (unlike drill bits.) Grr.
*>
*>How are the tip of the bits shaped? If they are flat like a normal milling
*>bit then this may be difficult, but if they are V shaped like a countersink
*>bit I would be tempted to try a normal carbide tipped drill as a bit if a
*>fine enough one was available. It may be necessary to grind the tip to a
*>sharp point, but you may get away with it for a quick development board
*>without doing this or using an expensive tip.

Try a normal carbide drill and break it off about in the middle. Wear
goggles. The end will be unbelievably sharp and work fine for milling
phenolic and delrin. The shape is right (one long tooth one shorter and
usually the middle is hollow or recessed due to the bit thickness and
shape). I have used it with success in a pinch. The slight off center
thrust and vibration turned out not to be problems (I used ~20k rpm). It
can also drill through holes (not recommended with a normal router bit).

To modify a Lexmark Z31:
1. disassemble the plastic case.
you'll see a steel rod (bar) guiding the ink tray
this rod (bar)is fixed in two holes, at its edges, with two springs
2. take out the rod (bar)
3. enlarge in the UP direction the two fixing holes, using a small round
file, with 1.6mm
the holes will became oval
4. modify the shape and the fixing method of the two springs, as to force
the rod UP
originally they force the rod down
5. lose the springs on the paper guides as to allow the PCP to pass smothly.

That's all.
You can move a A4 to A5 size PCB without problems.

A more evaluated way is to enlarge the two holes with 2.1mm and to
construct a .5mm tray with 1.6mm edges.

Remains unsolved: the ink problem.
Cristian

>Well, I know I'd be interested. Perhaps you can setup a page on
>piclist.com about this?
>
>Josh

Cristian, try to print as usual on a piece of PCB, then quickly spray
paint the board as it comes out of the printer, with laquer. Wave it a few
times in air to dry the laquer a little and put it in a tray with water
and alcohool (Vodka may work). The bubble ink should dissolve and take the
laquer with it, leaving the laquer only where there was no bubble ink.

This sounds good to me cause this is where I have the biggest problems as a hobbyist to produce crisp clear images on the pcb, cause the laminate always shifts around. So if I can print directly on the pcb it would also help with light creeping in from the sides and you would get a very crisp and neat layout on your pcb. To me this is the way to go but light sensitive laminated pcb's are very expensive in South Africa and would for that reason still would like just to print the tracks on the pcb and remove the copper chemically.

*>Hey Roman
*>
*>How about using an inkjet to print on UV sensitised laminate, and then
*>expose it using the inkjet print as a mask. This will get you around the
*>water based ink problem if it works.

There are a couple of printers on the market that will print directly to a
pcb.
Caracterized by what is known as a straight paper path, they also use
non-waterbased ink.
They are specially designed to print on stuff like CD's and hard plastic.
(Stuff without a pourus surface for ink to sink into.)

I don't have any particular brand for you, but I have seen them in action.

This sounds good to me cause this is where I have the biggest problems as a
hobbyist to produce crisp clear images on the pcb, cause the laminate always
shifts around. So if I can print directly on the pcb it would also help with
light creeping in from the sides and you would get a very crisp and neat
layout on your pcb. To me this is the way to go but light sensitive
laminated pcb's are very expensive in South Africa and would for that reason
still would like just to print the tracks on the pcb and remove the copper
chemically.

No offense intended, and I wish you luck, but... That's not "done and
working." That's a plastic prototype with a stylus sitting where you
need a high speed cutter. I thought about making my own PCB mill. I
even had the "polar coordinates will simplify the mechanics" idea. I
suspect it might work for drilling (and let's face it, drilling is a
major PITA that resist-squirting injets won't solve.) But I looked at
the existing commercial tables (T-Tech, LPKF) and decided that there
was an awful lot of MECHANICAL engineering in between something like
the prototype pictured on sourceforge and something that would
actually work. The commercial units have BIG THICK aluminum tables
and weigh ... a lot. The motors and solenoids that they're using are
nasty-looking. It's not just a matter of accurately moving a table
under a tool; you have to do that WHILE the tool is pushed into
contact with your work hard enough to have it cut through metal.
Without deforming anything. Seems to me like it'll be hard...

>Cristian, try to print as usual on a piece of PCB, then quickly spray
>paint the board as it comes out of the printer, with laquer. Wave it a few
>times in air to dry the laquer a little and put it in a tray with water
>and alcohool (Vodka may work). The bubble ink should dissolve and take the
>laquer with it, leaving the laquer only where there was no bubble ink.
>
>Try it and let us know ?
>
>Peter

>*>How about using an inkjet to print on UV sensitised laminate, and then
>*>expose it using the inkjet print as a mask. This will get you around the
>*>water based ink problem if it works.
>
>This should be tried. Good idea.
I've used a Sharpie pen mounted in a SweetPea plotter to make boards before.
1- I wonder if you could drive a print head with a Sharpie attached to it?
(print head movement Y axis - board movement X axis)
2 - What I really wonder is, could you expose an UV sensitised laminate
with a laser pen attached to a print head... ?

> Now there's an idea!!!
>
> You need to find out what ammount of UV you need and then what
source to
> use.
> Then, just make a plotter-jig with X/Y movement and some defined
pitch.
>
> This could be really cool. Too bad normal laser-pens atre way too
low
> wattage.
> You would need an hour on each point of more!
>
> Kyrre
Just a thought on the subject.. I may be very wrong.
As I recall, laser light is a VERY specific wavelength, not the usual
mix of assorted wavelengths that we perceive as white.
If the photosensitive material needs to be exposed by UV, I would
think that an off-the-shelf red laser pointer might never expose the
surface at all.

I like the idea though. It could offer great precision without
excessive wear on the printer parts.

If my beliefs regarding laser light are incorrect, I'm sure some
better educated person will point this out.

Well, my observation is something like "more watts per unit emissive
area than the tradtional BLB fluorescent bulb, and more easilly
focusable to a point as well. Of course, BLB exposures for most resists
are on the order of 10 minutes, right? Getting intensities high enough
for "human visible" plotter speeds is probably quite a challenge with
any UV technology. Even those high-intensity UV curing guns your
dentist has need multiple 10s of seconds of exposure...

I wonder if there's some sort of dual-chemical system that could be
used. Coat board with (water soluble) Part A, injet or plot with (water
soluble) Part B. Where they touch each other, you get water-insoluble
and etchant-resistant substance C. Wash off the extra "part A" and
you're all set. Alcohol soluble chemicals might work too (Hmm. And
that might include epoxies...)

OTOH, Metal capillary (hypodermic?) tubes filled with melted wax have some
attractions. No clogging just because some solvent evaporates...

Robert Shanks wrote:
>
> >*>How about using an inkjet to print on UV sensitised laminate, and then
> >*>expose it using the inkjet print as a mask. This will get you around the
> >*>water based ink problem if it works.
> >
> >This should be tried. Good idea.
> I've used a Sharpie pen mounted in a SweetPea plotter to make boards before.
> 1- I wonder if you could drive a print head with a Sharpie attached to it?
> (print head movement Y axis - board movement X axis)
> 2 - What I really wonder is, could you expose an UV sensitised laminate
> with a laser pen attached to a print head... ?

It's actually easier to move around a piece of fibre. You put the
laser at one end, and the flat fiber on the plotter in place of a
pen tip. Works a charm (according to some long lost web site I read).
(and and LED works just fine too).

If you want a really fine spot you can use a disposable camera lens
to focus the beam to an even finer point.
Be aware that laser diodes do not emit a round beam.
It is oval shaped and requires special optics to
get a fine gaussian beam. On the other hand you could just blast
it through a pin hole to get something appropriate to the scale
a DIY board would handle.

When using light for writing, you MUST modulate the beam intensity
with the plotter velocity information to get a uniform exposure width.
(Been there, done that with Tektronix 4662 flat bed plotter)

This sounds viable, but there are issues;
* UV coated boards are;
* expensive
* go off over time (that sucks)
* get scratched (and that sucks)
* hard to cut small without damaging coating
* NEED EXTRA PROCESSES!

Coupled with the extra problems of getting a suitable
UV plotter, which sounds mugh harder than just finding
a waterproof ink that works in a bubblejet.

I like to design things from the back forward, as
the SOLUTION is what you really want, not the process.
What's that great Japanese saying? "Fix the solution,
NOT the problem" or something like that. :o)

I like XYZ routers and have one semi finished in
my workshop, but wouldn't use it for PCB routing
for so many reasons;
* REALLY NOISY!
* PCB dust is very abrasive and wrecks tools
* PCB (glass!) dust is very bad to breathe
* huge rigidity is needed to stop jumping which
wrecks tools
* needs supervising (tools dull and break)
* produces worse board than etching, especially
for SMD
* slower and less accurate than etching for larger
boards, routing will sometimes break fine tracks,
mechanically stresses track glue even before
soldering stresses start
* forces you to remove minimum copper, and hence
compromise board design or soldering ease to
reduce tool costs

I really like Cristian's suggestion to just modify
a cheap common bubblejet to feed PCB thickness
material. I also think it is worth going that extra
step to make a carrier "plate" or "tray" that can
be just made out of PCB too, which is a thickness
on the edges (2 PCB?) to always feed well, and will
hold one or more small PCB on the tray as it feeds.
Using the standard feed tray should allow some simple
guides to ensure reliable tray feeding, and you can
use any tiny bits of PCB you have around.

The small PCB can be held down by blu-tack or anything
as it has no roller contact stresses. Once the PCB
is "inked" it can be etched and provide a good PCB
for SMD parts, with none of the height variations or
track edge dags that a router would make.

The SMD parts can be placed very quickly with a
standard paste syringe and the aquarium pump and
finger-hole vacuum pencil described by Alexandre,
cheap and much faster than through-hole bending
threading and snipping.

Soldering can be done with a cheap hot air gun of
the type used for paint stripping or the solder
sucker hot air gun discussed on the list about
a year back. This will be quicker than the equivalent
through-hole work and solders the entire board in
a few seconds without eye and hand strain.

And this system would be perfect for hobby style
production runs of 5 to 20 that a large portion of
piclist members would like to do. How many of us
pay for board production when we only need a few
gizmos made?
-Roman

It is a idea, but the ink doesn't adhere to photoresist.
The result looks like printing on a grease surface.
Cristian
>On Fri, 8 Nov 2002, Alan B. Pearce wrote:
*>How about using an inkjet to print on UV sensitised laminate,
>This should be tried. Good idea.
>
>Peter

> If you want to build a PCB Mill, think "light" and "round"
> http://freeandeasy.sourceforge.net Done and working. Very fast and
> suprizingly accurate.
>
>No offense intended, and I wish you luck, but... That's not "done and
>working." ..... Seems to me like it'll be hard...
>
>BillW

You're not supposed to print on foto-resist.
The whole point would be to print directly on bare copper PCB.
The ink will protect the copper just as the photo-resist would as long as it
is waterproof and thick enough.

> It is a idea, but the ink doesn't adhere to photoresist.
> The result looks like printing on a grease surface.
> Cristian
> >On Fri, 8 Nov 2002, Alan B. Pearce wrote:
> *>How about using an inkjet to print on UV sensitised laminate,
> >This should be tried. Good idea.
> >
> >Peter
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways. See http://www.piclist.com/#archives for details.
>
>
>

*>>*>How about using an inkjet to print on UV sensitised laminate, and then
*>>*>expose it using the inkjet print as a mask. This will get you around the
*>>*>water based ink problem if it works.
*>>
*>>This should be tried. Good idea.
*>I've used a Sharpie pen mounted in a SweetPea plotter to make boards before.
*>1- I wonder if you could drive a print head with a Sharpie attached to it?

You are about to reinvent the photoplotter. Why UV when you can paint
directly ? It would be much more interesting to develop an inkjet head
(single nozzle) and paint with that. I half want to do that (probably in
one of my future lives). I'd go with piezo or electrodynamic ejection and
electrostatic deflection. The first inkjets used this technology afaik.
Some industrial printers (production line printers - like the kind that
print serial numbers and barcodes on foamboards and soft material packs)
still do afaik. I'd probably use plain refined wax as ink. It would take
me man-months to reach the required resolution (est. 300dpi). Btw certain
kinds of wax could be tried in a normal bubble jet print head assuming it
has an extra heater added to it (power resistor + thermostat worked into
the reservoir). Wax melts well under 100C and it should leave the plastic
alone. It would probably require a major rework of the ink channels though
and probably different timing to drive the heads (or different voltage).

*>It is oval shaped and requires special optics to
*>get a fine gaussian beam. On the other hand you could just blast
*>it through a pin hole to get something appropriate to the scale
*>a DIY board would handle.

Pinholes do not sharply image laser beams. You would get a first class
diffraction pattern from it. You would need to pass it through a pinhole
and image the pinhole with an additional lens. This will lose a lot of
power.

Fiber that passes UV is expensive.

CD laser heads include all the parts required to make a secondary-scanned
imaging device, if the laser and mirror are replaced with a UV one. This
could be mounted on a plotter and do the job. Probably with fixed focus.
The tracking coild could be driven with ac to make a wider path.

Down to about 395nm (which is deep purple, more or less, but well capable of
inflicting UV-style fluorescence and such in most long-wave UV materials),
you're looking at less than $3 per LED. I bought some from Hong Kong
without any problems:

"Peter L. Peres" wrote:
>
> On Sun, 10 Nov 2002, Robert Rolf wrote:
>
> *>It is oval shaped and requires special optics to
> *>get a fine gaussian beam. On the other hand you could just blast
> *>it through a pin hole to get something appropriate to the scale
> *>a DIY board would handle.
>
> Pinholes do not sharply image laser beams. You would get a first class
> diffraction pattern from it. You would need to pass it through a pinhole

Yes, you do, but it's a much better shape than what you get with a
straight beam. And two stacked pinholes gets a near perfect beam
when the 2nd PH is a touch bigger than the first and removes the 1st
order diffraction ring.

> and image the pinhole with an additional lens.

That works too.

>This will lose a lot of power.

Yes, it does. Tradeoffs as always.

> Fiber that passes UV is expensive.

Who said anything about UV? The guy was talking about using a pen
laser. That's red and is incapable of exposing most UV resist. Plastic
fiber would suffice for photosensitive resist with any kind of red
sensitivity. Of course he could use a blue LED to get closer to the
exposure band level.

> CD laser heads include all the parts required to make a secondary-scanned
> imaging device, if the laser and mirror are replaced with a UV one. This

Great idea but the focus detectors probably wouldn't work at UV wavelengths.

> could be mounted on a plotter and do the job. Probably with fixed focus.
> The tracking coild could be driven with ac to make a wider path.

Except that it only tracks in one axis, so you'd have a hard time
drawing wide lines in the other axis.

So what's wrong with printing to film and just exposing the board
through it? This makes the replication process much faster, and
makes two sides boards easier too.

Hi Cristian, I was just given a Lexmark Z22, so I opened it up. I don't
know how similar it is to the Z31, but I have a few questions. Your
method seems like it would work on this printer as well, but I think it
needs a couple modifications. I found the steel rod ok, and I think I
can figure out how to modify the metal frame so the rod sits up higher.
Is your measurement (1.6mm) the amount you extended the hole? I think I
can get the springs underneath the rod, and push it up instead of down.
But, what springs did you mean in the paper path? There are a set of
mini rollers with springs that push the paper against the feed roller.
Then there are a set of smaller springs that push the paper against a
roller farther downstream, presumably to eject the piece after printing.
The one other problem I see is that there is no slot on the back of the
printer, so I guess one would have to be cut to allow a perfectly flat
paper path.

Anyone having any luck with ink issues? Has anyone tried india blue?

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
-Douglas Adams

>
> No need for a special page. No specialtools, no extra $$.
>
> To modify a Lexmark Z31:
> 1. disassemble the plastic case.
> you'll see a steel rod (bar) guiding the ink tray
> this rod (bar)is fixed in two holes, at its edges, with two springs
> 2. take out the rod (bar)
> 3. enlarge in the UP direction the two fixing holes, using a small round
> file, with 1.6mm
> the holes will became oval
> 4. modify the shape and the fixing method of the two springs, as to force
> the rod UP
> originally they force the rod down
> 5. lose the springs on the paper guides as to allow the PCP to pass smothly.

*>Great idea but the focus detectors probably wouldn't work at UV wavelengths.

I mean without the detectors. Just use the head as an optical unit after
gluing a blue led inside it (after removing the half silvered mirror and
the detector). There would be several clever schemes to use autofocus but
I'd say one step at a time here.

*>> could be mounted on a plotter and do the job. Probably with fixed focus.
*>> The tracking coild could be driven with ac to make a wider path.
*>
*>Except that it only tracks in one axis, so you'd have a hard time
*>drawing wide lines in the other axis.

True.

*>So what's wrong with printing to film and just exposing the board
*>through it? This makes the replication process much faster, and
*>makes two sides boards easier too.

"Peter L. Peres" wrote:
I wrote:
> *>So what's wrong with printing to film and just exposing the board
> *>through it? This makes the replication process much faster, and
> *>makes two sides boards easier too.
>
> We alreay know how to do that ;-)

Maybe there is a GOOD reason why we print to film and then expose?
BTW used laser printers (LJIIs & LJIII) can be had for $25 at most
computer recycling places. They print gread blacks and are probably
quicker from print to etch time than any inkjet direct to PCB kludge.

And if you are in a larger center you can get photoplots from PDF
files at most larger print shops. $10.00 or so for a 8"x10" plot.

2. In a laser printer do they statically charge the drum so it picks up the
toner. If so perhaps the copper could be charged. Using a laser out of one
of the $25 to discharge the copper areas to be removed. Then dusted, heated
then etched... starting to sound a little involved perhaps

> 1. How do they originally get the copper to stick to the board.
>
> 2. In a laser printer do they statically charge the drum so it picks up the
> toner. If so perhaps the copper could be charged. Using a laser out of one
> of the $25 to discharge the copper areas to be removed. Then dusted, heated
> then etched... starting to sound a little involved perhaps

Especially considering the apparent difficulty of convincing certain areas
of a large sheet of conductive copper sheet to assume a significantly
different electrostatic charge potential than adjoining areas... I'd
really like to see you figure that one out!

Laser printer photoreceptors (drums, belts, etc) are coated with various
materials chosen for their suitability for retaining a static charge.
The big Xerox series I spent a lot of time wokring on used selenium doped
with arsenic, IIRC... nasty stuff if you need to polish one out as I have
done countless times. Anyway, copper would disrupt things pretty much
completely.

Hard drive platters are coated with a "paint" made with microscopic
particles of various metal oxides, it's those that hold the magnetic
charge. The platter itself is non-magnetic (aluminum, magnesium or
glass).

Dale
---
We are Dyslexia of Borg.
Fusistance is retile.
Your ass will be laminated.

On Wed, 13 Nov 2002, Richards, Justin P wrote:

> How is it done on the Drum. I thought they were metallic also. I also
> wonder how they have different magnet moment polarities so close together on
> a Hard drive platter.

Dale Botkin wrote:
>
> On Tue, 12 Nov 2002, Richards, Justin P wrote:
>
> > 1. How do they originally get the copper to stick to the board.
> >
> > 2. In a laser printer do they statically charge the drum so it picks up the
> > toner. If so perhaps the copper could be charged. Using a laser out of one
> > of the $25 to discharge the copper areas to be removed. Then dusted, heated
> > then etched... starting to sound a little involved perhaps
>
> Especially considering the apparent difficulty of convincing certain areas
> of a large sheet of conductive copper sheet to assume a significantly
> different electrostatic charge potential than adjoining areas... I'd
> really like to see you figure that one out!

The charge is stored and imaged on the DRUM inside the toner cartridge.
It is then transfered to the paper, which is why you need a bit of flex
there.
They don't store charge on the paper because it's just too hard to control the
conductivity between reams (humidity varies all over the place).

Even the original Xerox 810 (the one where you manually moved the charged
plate from the charger to the contact exposure unit to the toner tray to
the fuser) used an intermediate charge transfer method.

> The charge is stored and imaged on the DRUM inside the toner
> cartridge. It is then transfered to the paper, which is why you need a
> bit of flex there. They don't store charge on the paper because it's
> just too hard to control the conductivity between reams (humidity
> varies all over the place).

Good point. I wonder, though, what effect a solid copper sheet hitting
the charged drum surface would have. Also in a normal laser
printer/copier setup, the paper is charged before being pressed against
the drum.

In short, while there may be a theoretical way to get it to work, I
strongly suspect the practical difficulties in getting a laser printer
modified to print on copperclad board will be far too great for the
average (or even above average) person. The process depends completely on
controlled electrostatic charges, and I think the presence of a sheet of
copper is going to disrupt things beyond the point where you can get a
conumer grade laser to deal with it. Of course I could be wrong, don't let
me stop anyone from trying, but good luck. I've spent far too many hours
in the bowels of lasers (from LJ-I to Xerox 3700, 8700, 9700, Siemens
1km/hr continuous feed cold fusion, you name it) just to get them to print
on various types of *paper* reliably. Remember, the end result has to be
not just toner on copper, but a near perfect image.

It seems Z22 is a little different printer.
That minirollers you have to loose a little to allow easy transport of the
thick PCB.
At 13:43 11/11/02 -0600, you wrote:
>Hi Cristian, I was just given a Lexmark Z22, so I opened it up. I don't
>know how similar it is to the Z31, but I have a few questions. Your
>method seems like it would work on this printer as well, but I think it
>needs a couple modifications. I found the steel rod ok, and I think I
>can figure out how to modify the metal frame so the rod sits up higher.
>Is your measurement (1.6mm) the amount you extended the hole?
yes
I think I can get the springs underneath the rod, and push it up instead of
down.
>But, what springs did you mean in the paper path? There are a set of
>mini rollers with springs that push the paper against the feed roller.

Those rollers with springs.

>Then there are a set of smaller springs that push the paper against a
>roller farther downstream, presumably to eject the piece after printing.

No modification there.

>The one other problem I see is that there is no slot on the back of the
>printer, so I guess one would have to be cut to allow a perfectly flat
>paper path.

Is that about the plastic case?
>
>Anyone having any luck with ink issues? Has anyone tried india blue?

>
>Josh
>--
>A common mistake that people make when trying to design something
>completely foolproof is to underestimate the ingenuity of complete
>fools.
> -Douglas Adams
>
>Cristian wrote:
>>
>> No need for a special page. No specialtools, no extra $$.
>>
>> To modify a Lexmark Z31:
>> 1. disassemble the plastic case.
>> you'll see a steel rod (bar) guiding the ink tray
>> this rod (bar)is fixed in two holes, at its edges, with two springs
>> 2. take out the rod (bar)
>> 3. enlarge in the UP direction the two fixing holes, using a small round
>> file, with 1.6mm
>> the holes will became oval
>> 4. modify the shape and the fixing method of the two springs, as to force
>> the rod UP
>> originally they force the rod down
>> 5. lose the springs on the paper guides as to allow the PCP to pass

I've tried various techniques for getting PCB resist onto the copperclad -
including trying to get it to go through various kinds of printer - nothing
worked well. Back in the days of the Apple II, I had a plotter, into which
I put an indelible ink pen - the software then drew the tracks straight on
to the copper. This was OK, but not capable of really thin or close tracks.
It was fine for the few prototype PSUs I was working on at the time....

The only way to use a laser printer (in my experience) is to print the
artwork on to draughting film, and then go the photograpic route....

Arrgh! Now I'm fed up with you guys trying to do charge-pickup printing to
a conducting plate when it can be done much simpler...

OK, what I'd like to see is a system using laser to heat/melt copper powder
so that it sticks to a bare fiberglass board. To do this you will first
have to coat the board and that wouldn't be hard as fine grained copper acts
a bit sticky by itself and youy can simply distribute it aboput evenly over
the board and press it down with a roller.
Now... To heat the copper we use a laser. The cool thing now is that we
can either do raster mode, or we can do vector-based tracing. The latter
would give great control :-)

Problem is getting a laser powerful enough. If it's focused finely enough
this shouldn't be too big a problem...

> OK, what I'd like to see is a system using laser to heat/melt copper
powder
> so that it sticks to a bare fiberglass board. To do this you will first
> have to coat the board and that wouldn't be hard as fine grained copper
acts
> a bit sticky by itself and youy can simply distribute it aboput evenly
over
> the board and press it down with a roller.
> Now... To heat the copper we use a laser. The cool thing now is that
we
> can either do raster mode, or we can do vector-based tracing. The
latter
> would give great control :-)
>
> Problem is getting a laser powerful enough. If it's focused finely
enough
> this shouldn't be too big a problem...
>
> Whaddya think ?

You should look into the melting temperature of copper with respect to the
temperature at which the resin in the fiberglass stops working.

Doesn't sending your boards to Advanced Circuits or PCB Express sound
pretty good by now? It's been entertaining watching the each flaky idea
trump the next on this thread, but it's getting a bit rediculous now.

I recall recently (this year) a German University is experimenting
with printable circuits on plastic laminate technology - mainly for
circuits that require foldabilty - such as sight and medical
circuits. Perhaps their printing method could be worth looking at?

Doesn't sending your boards to Advanced Circuits or PCB Express sound
pretty good by now? It's been entertaining watching the each flaky idea
trump the next on this thread, but it's getting a bit rediculous now.

Heh. Which vendors WILL step&repeat a small board across some larger panel
as part of their low-cost prototype option? Most of them seem to explicitly
prohibit this, some with language that sounds like it prohibtis YOU from
doing it too...

Hahaha... glad you finally said it, Olin! I've been chuckling and
biting my tongue for days now!

I am always amazed how so many bright people on the PIC list can take a
very simple problem and turn it into a Rube Goldberg-like solution. I
certainly understand the hobbyist and "starving student" perspective,
where time is abundant and money is not -- heck, I've been there too.
Innovative and creative thinking is a good thing, but common sense still
goes a long way.

Wasn't there a company selling copper on 1-mil plastic, designed to be
printed on and then glued / epoxied onto a substrate? I remember reading
about it in Popular Electronics ages ago... You'd run this stuff through
a laser printer, align both sides of the board (the author used .100"
perfboard as a substrate, and did everything on .100" centres), contact
cement it down, and etch. Clean toner, and you're done.

They offered to prototype it on a single panel with 200 copies.
As long as we would accept about 1-2% crossouts...
We would pay about 450$ everything included.
That ain't too bad is it ?

Well, it really sucks compared to the ~$50 to $200 most board houses seem
to be offering for their "minimum" proto price ($50 has no silkscreen or
soldermasks.) It's not too bad if you're sure that the board works and
you have an market that will use 200 of them. I had more in mind filling
up one of the LITTLE prototypes (30 square inches?) with boards your
size (~15 board?)

cdb wrote:
>
> >From many a flaky idea a catalyst springs and someone says if I mix A
> with Z and play with F hey presto look at my new world beating
> invention!
>
> The long in the tooth and wise old scientists and engineers then all
> look bewildered, scoff, and then think @#$%^& why didn't I think of
> that? Such is the mother of invention!

Well said Colin,
I'd rather be a "flaky backyard inventor" than
a "competent" engineer stagnant in mediocrity.
Very little satisfaction in playing follow the
leader.
-Roman

> Doesn't sending your boards to Advanced Circuits or PCB Express sound
> pretty good by now? It's been entertaining watching the each flaky idea
> trump the next on this thread, but it's getting a bit rediculous now.

My original spec of using special ink in a
bubblejet followed by etching and SMD hot air
soldering is not flaky at all.

The only real issue is finding a suitable ink,
and then the system would be many times cheaper
and faster than any commercial board house and
suitable for one-off with tiny PCBs.

I have discussed the ink issue with my girlfriend
(who is an industrial chemist) and the problems
should be simple so solve if anyone gave a damn.

I also checked the ink cartridge in my bubblejet,
it says "solvent = isopropyl alcohol" so obviously
the plastic and all mechanisms are alcohol safe.

This should make it EASY to find a suitable ink
or lacquer.

The problem of filling the bubblejet cartridge is
already solved with refil kits available at office
supply stores.

Cristian has solved the PCB feed issues or come
some of the way to solving them.

I have a piece of PCB cleaned and ready and am
trying different ink and lacquer ideas as the
ideas arise but I am busy with some important
projects right now.

Maybe if the brain bank spent less criticising
and saying "go to PCB house" (which is NO help
to anyone) some clever person here could find a
really smart ink solution. Or is it just Cristian
and myself who think that a "5 mins to soldering"
prototyping system is worth building?
-Roman

> Maybe if the brain bank spent less criticising
> and saying "go to PCB house" (which is NO help
> to anyone) some clever person here could find a
> really smart ink solution. Or is it just Cristian
> and myself who think that a "5 mins to soldering"
> prototyping system is worth building?
> -Roman

One of the "rules" of creative meetings is to throw anything on
the table, no matter how whacky. If you don't, you never know
what possibilities may be missed or what tangents arise from
so-called outrageous ideas

I think this was intended at my flaky idea of statically charging etc then
melting toner on the copper.

Industrial chemist hey, that's handy.

Someone mentioned the ink used to date code products like soft drink
bottles. It certainly is water insoluble, however I was led to believe the
stuff is quite poisonous. They had quite a procedure at coca-cola for the
refiling and disposing of empty containers.

Justin

<Roman said>
My original spec of using special ink in a
bubblejet followed by etching and SMD hot air
soldering is not flaky at all.
<>

nitrocellulose is somewhat soluble in isopropyl alcohol. Common stuff,
over here (think NC laquer rather than gunpowder. Or "nail polish")

Another possibility is some of the micro-fine powdered polyethylene (again,
used in the cosmetic industry.) I probably wouldn't work quite by itself,
by you could probably put it in a water/alcohol carrier and then bake it
on to fuse it to the copper. (rather similar to laser printer toner in that
respect.) For that matter, I wonder what's in those opaque-ink "gel" pens
that are appearing all over (these have a light-colored base that works on
black paper, but they're fluid enough to work in more-or-less standard
ballpoint mechanisms...)

I have never had any problems with them. Have used them at least half a
dozen times for plated through hole one-off boards. They delivered when
they said they would at the price they quoted. No problems with the
quality. Only hassle is the silly file format they require.

William Chops Westfield wrote:
>
> nitrocellulose is somewhat soluble in isopropyl alcohol. Common stuff,
> over here (think NC laquer rather than gunpowder. Or "nail polish")
>
> Another possibility is some of the micro-fine powdered polyethylene (again,
> used in the cosmetic industry.) I probably wouldn't work quite by itself,
> by you could probably put it in a water/alcohol carrier and then bake it
> on to fuse it to the copper. (rather similar to laser printer toner in that
> respect.) For that matter, I wonder what's in those opaque-ink "gel" pens
> that are appearing all over (these have a light-colored base that works on
> black paper, but they're fluid enough to work in more-or-less standard
> ballpoint mechanisms...)

Thanks BillW, good ideas. Really anything soluble
in alcohol that dries to a waterproof layer should
work, as a decent etch resist anyway. Making sure
it prints well in a bubblejet head and doesn't gum
up the head when not is use is a fraction harder.

I tested some bubblejet ink on a few surfaces, one
thing I did note is that it is VERY slow drying,
and doesn't quite dry at all unless it soaks into
paper which seems to dry it. I'm guessing this is to
avoid drying in the head and gunging it up.

I think that shellac might be usable, it is organic
and non toxic, dissolves totally in alcohol and can
be diluted to the right viscosity. I'll buy a
paint viscosity measure and some bubblejet refil
ink and get a viscosity reading unless someone has
more accurate equipment. :o)
-Roman

> Someone mentioned the ink used to date code products like soft drink
> bottles. It certainly is water insoluble, however I was led to believe the
> stuff is quite poisonous. They had quite a procedure at coca-cola for the
> refiling and disposing of empty containers.

Sounds expensive too, ie used in very small
amounts per "numbering". I'm thinking some
type of lacquer or coating that is fairly cheap
and alcohol or alcohol/water soluble, but dries
to waterproof.

Even if clear it can easily have some dye added
making it easier to proof check the PCB.

If I get out tomorrow I might visit the arts and
crafts shop and see if they have anything. :o)
-Roman

> William Chops Westfield wrote:
> >
> > nitrocellulose is somewhat soluble in isopropyl alcohol. Common
> > stuff, over here (think NC laquer rather than gunpowder. Or "nail
> polish") >
> > Another possibility is some of the micro-fine powdered polyethylene
> > (again, used in the cosmetic industry.) I probably wouldn't work
> > quite by itself, by you could probably put it in a water/alcohol
> > carrier and then bake it on to fuse it to the copper. (rather
> > similar to laser printer toner in that respect.) For that matter,
> > I wonder what's in those opaque-ink "gel" pens that are appearing
> > all over (these have a light-colored base that works on black paper,
> > but they're fluid enough to work in more-or-less standard ballpoint
> mechanisms...)
>
> Thanks BillW, good ideas. Really anything soluble
> in alcohol that dries to a waterproof layer should
> work, as a decent etch resist anyway. Making sure
> it prints well in a bubblejet head and doesn't gum
> up the head when not is use is a fraction harder.
>
> I tested some bubblejet ink on a few surfaces, one
> thing I did note is that it is VERY slow drying,
> and doesn't quite dry at all unless it soaks into
> paper which seems to dry it. I'm guessing this is to
> avoid drying in the head and gunging it up.
>
> I think that shellac might be usable, it is organic
> and non toxic, dissolves totally in alcohol and can
> be diluted to the right viscosity. I'll buy a
> paint viscosity measure and some bubblejet refil
> ink and get a viscosity reading unless someone has
> more accurate equipment. :o)
> -Roman
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
>
>

Roman Black wrote:
.
> I tested some bubblejet ink on a few surfaces, one
> thing I did note is that it is VERY slow drying,
> and doesn't quite dry at all unless it soaks into
> paper which seems to dry it. I'm guessing this is to
> avoid drying in the head and gunging it up.
.

May be heating PCB's copper when printing could help?

Mike.

> Being able to dry boards and cure glues and inks
> at 40'C or 50'C is very handy, it is one of our
> most used pieces of equipment.
>
> Another handy technique is to put the board on
> the table and a 60W "arm type" desk lamp 3"
> above it, this gives a fairly constant 50'C.

Roman Black wrote:
.
> Maybe if the brain bank spent less criticizing
> and saying "go to PCB house" (which is NO help
> to anyone) some clever person here could find a
> really smart ink solution.
.
He is the owner of his "brain bank". And I'm happy
he chose to spend his "brain bank" resources to
provide some negative feedback on the question,
quite reasonable feedback, in my opinion.

Mike.

PS:
Through my weak English I failed to find appropriate
quotation about somebody's willingness to die for his
opponent could criticize him. :-)

When I played with this kind of thing on an old HP plotter, the recommended
resist pen ink was a staedler red felt marker. I replaced the felt soaked
core of the standard plotter pens with a scavanged staedler pen. You can
get a bottle of the same ink (although it's special order around here.).
Might try to see if it will work in an ink jet nozzle.

I found I still had a box of these... Staedtler lumocolor 313 --Red (a
little better etch resist properties than the black). These can write on
glass, metal, etc. w/o beading up.
----- Original Message -----
From: "Dal Wheeler" <RemoveMEdwheelerKILLspamTakeThisOuTinsightek.net>
> When I played with this kind of thing on an old HP plotter, the
recommended
> resist pen ink was a staedler red felt marker. I replaced the felt soaked

The high power necessary to evaporate the copper layer will burn the
substrate for sure.
Cristian
At 16:16 12/11/02 PST, you wrote:
>I believe LPKF does has a laser-based version of the PCB router (burns AWAY
>copper by laser...)
>BillW

> When I played with this kind of thing on an old HP plotter, the
recommended
> resist pen ink was a staedler red felt marker. I replaced the felt
soaked
> core of the standard plotter pens with a scavanged staedler pen. You
can
> get a bottle of the same ink (although it's special order around here.).
> Might try to see if it will work in an ink jet nozzle.

Back in 1980 I was right out of school and working for HP. I wanted a way
to make my own circuit boards for personal projects like you guys are
talking about. I even wrote a simple layout program on the desktop
computer I had. You entered coordinates for net points in a text file and
it would compute the tracks and mark whatever it couldn't route. The
problem was how to get the information out of the computer onto a circuit
board.

There was a pen plotter available that could be hooked to the computer, so
I programmed it to draw filled areas by using a raster pattern. At first
I just had it draw onto a piece of paper, then converted that to a
Kodalith negative in the darkroom, then used that to expose boards. At
the time there was photoresist available that came in two parts. It ended
up being a thick greenish liquid that you painted on the copper then let
it dry. I think it was called "Resolve" or something like that. It was
not lacquer based as everything I've seen since then. After exposing the
board, you rinsed away the unexposed areas with plain water, then baked
the board to cure the remaining stuff onto the copper, then etched
normally.

This process worked OK, but there were problems. The worst one was that
it would use up one or more of the little felt tip plotter pens per board.
I tried to fix that by cutting the top off one of them and manully filling
it with ink before a run. That helped, but it made large blotces in the
beginning, and needed refill steps along the way. Then I modified a
"liquid ink" pen mount on the plotter. These have no ball point or felt
tip, just a cappillary with a tube to an ink reservoir. The cappillary is
thin enough so that the ink doesn't come pouring out until the bubble
touches the paper. This worked much better, but was quite a mess to use
and clean.

Then I began experimenting with using dark ink and writing directly onto
the photoresist layer. That sortof worked, but the ink apparently didn't
block the light that well or otherwised messed up the photoresist. Then I
tried "writing" a resist layer directly to the copper using the liquid ink
pen. I changed jobs and lost use of the equipment before I found an ink
that would both adhere to copper and stay there during the etching
process.

If you guys really want to try direct writing resist onto a copper board,
I suggest looking into a liquid ink pen driven by a plotter. Liquid ink
pens will take just about any ink, and can deliver large quantities of it
unlike any other pen. It will be hard enough to find a suitable ink
without also requiring it to work in an inkjet printhead that is finely
tuned for a specific type of ink.

Since I was experimenting with this 22 years ago, I've noticed some
substances that might be worth a try as ink. One of these is a liquid
plastic you can get in toy stores. I think it's meant to immerse wire
loops in, then pull them out and let the "soap bubble" film dry into a
plastic membrane. I bet this stuff stands up to etchant, but I don't know
how well it might adhere to copper. I'm sure it is way too gloppy for an
injet head. The next thing I was going to try was polyurethane paint, but
never got to it.

> When I played with this kind of thing on an old HP plotter,
>the recommended resist pen ink was a staedler red felt marker.
>I replaced the felt soaked core of the standard plotter pens
>with a scavanged staedler pen. You can get a bottle of the
>same ink (although it's special order around here.).
> Might try to see if it will work in an ink jet nozzle.

I believe Staedtler make a substitute pen for fitting to plotters for doing
exactly this. The tip is a ceramic disc a couple of mm diameter, and it is
refillable. The pen is designed for plotting onto draughting film to plot
masters in a draughtmans office. I cannot remember, but I think the ink that
Staedler supply will also plot straight onto the copper surface of the
board. The ink capillaries down the pen in the way that Olin described, and
the ceramic tip is extremely hard wearing.

I saw this described in one of the electronics magazines, but cannot
remember just which one. It may have been Electronics Australia, or could
have been Elektor, or Electronics and Wireless World. Which ever one it was,
it would be over 5 years ago now. However I do seem to recall that someone
also had the information on the web. Unfortunately I do not seem to have
kept a link to it.

>
> On Wed, 13 Nov 2002, David Minkler wrote:
>
> > "I disagree with everything you say, but I will fight to the death for
> > your right to say it." - Voltaire to Helevetius
>
> Actually, I'm told it was Batrice Hall that said this *about* what
> Voltaire said.
>
> I may disagree with what you say, but I will defend to the death your
> right to mis-attribute this quote to Voltaire.
> -- Avram Grumer, rec.arts.sf.written, May 2000
>
> 8-)
> (and YES, I did have to look it up!!!)
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Why did I forget it was Voltaire?
Googling with "quotations disagree voltaire" answered.
Men, I am stupid.

Mike.

> Dale Botkin wrote:
> On Wed, 13 Nov 2002, David Minkler wrote:
>
> > "I disagree with everything you say, but I will fight to the death
for{Quote hidden}

> > your right to say it." - Voltaire to Helevetius
>
> Actually, I'm told it was Batrice Hall that said this *about* what
> Voltaire said.
>
> I may disagree with what you say, but I will defend to the death your
> right to mis-attribute this quote to Voltaire.
> -- Avram Grumer, rec.arts.sf.written, May 2000
>
> 8-)
> (and YES, I did have to look it up!!!)

Kind of timely, I just recieved the Nov. 11, 2002 (or 11-11-02 for those on
the date usage thread) edition of Electronic Design magazine. It has the
LPKF circuitboard milling machine on the front cover. The website hast the
article in pdf if anyone is interested.

At $60K US (w/ 2 day operating instruction! yipee); it might be a while
before one finds its way into my basement. I'm hoping Roman comes up with
some kind of "Flakey scheme" that works. :') I've got a few home projects
that will never get sent off to a board house unless they start giving away
boards. Paying projects are never the issue.

BTW I did play with the thermal printer over the weekend and got the
transport to work (mostly), but the thermal bonding issues with the copper
surface were a problem... I'll see if I can't warm the surface up a bit
before printing. Also the ribbon breaks pretty easily with the
discontinuity of the cardboard carrier and the clad stock. It might not
work out at all. Here's hoping the ink jet route pans out.
-Dal

> Back in 1980 I was right out of school and working for HP. I wanted a way
> to make my own circuit boards for personal projects like you guys are
> talking about.

8< snip...

I used to have an old IBM six-pen plotter (a re-labeled HP 7475, I think,
B size flatbed). I had excellent luck using a .5mm permanent marker that
I found at an art store. I had a cut-down HP felt tip plotter pen body
that the new marker friction-fit into. By setting the plot speed down to
1 or 2 inches per second, I got near perfect boards every time. I was
only making single sided boards, but I suppose with enough work one could
probably get a double sided board done the same way.

The plotter moved the pen in the X axis and the paper in the Y axis by
means of a rubber lower roller and a grit-faced upper roller. I did find
I had to tape the PCB to a sheet of paper because the registration process
was at high speed regardless of the plot speed you had set, and the
rollers didn't grip the PCB material well enough to prevent slipping under
that kind of acceleration.

The pen was a common ultra-fine permanent ink pen, available in several
colors from the local art supply joint. Its only remarkable feature was
that it was small enough in diameter to fit into an HP pen body that had
the top and bottom removed so the pen gripper mechanism could hold onto
it. I used this setup numerous times with excellent results; the only
reason I didn't mention it long ago is that old HP plotters are kind fo
hard to come by any more. I think I did mention this on the list a couple
of years ago.

>
> On Wed, 13 Nov 2002, Olin Lathrop wrote:
>
> > Back in 1980 I was right out of school and working for HP. I wanted a way
> > to make my own circuit boards for personal projects like you guys are
> > talking about.
>
> 8< snip...
>
> I used to have an old IBM six-pen plotter (a re-labeled HP 7475, I think,
> B size flatbed). I had excellent luck using a .5mm permanent marker that
> I found at an art store. I had a cut-down HP felt tip plotter pen body
> that the new marker friction-fit into. By setting the plot speed down to
> 1 or 2 inches per second, I got near perfect boards every time. I was
> only making single sided boards, but I suppose with enough work one could
> probably get a double sided board done the same way.
>
> The plotter moved the pen in the X axis and the paper in the Y axis by
> means of a rubber lower roller and a grit-faced upper roller. I did find
> I had to tape the PCB to a sheet of paper because the registration process
> was at high speed regardless of the plot speed you had set, and the
> rollers didn't grip the PCB material well enough to prevent slipping under
> that kind of acceleration.
>
> The pen was a common ultra-fine permanent ink pen, available in several
> colors from the local art supply joint. Its only remarkable feature was
> that it was small enough in diameter to fit into an HP pen body that had
> the top and bottom removed so the pen gripper mechanism could hold onto
> it. I used this setup numerous times with excellent results; the only
> reason I didn't mention it long ago is that old HP plotters are kind fo
> hard to come by any more. I think I did mention this on the list a couple
> of years ago.
>
> Dale
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Ah. Stupid me, I hadn't even looked. Last time I did look for one was
several years ago, and they were hard to find then -- but eBay was barely
a startup at that time. You can do this with any of that series of HP
plotters, I think I also used a 7470 at the time.

I can't tell you guys how nice this setup works, though. The pens I found
are only a couple of bucks each, and I could go from layout to complete,
etched & drilled board in about an hour for a simple project. Lines were
very clean, you just have to remember you simply can't do 8 mil lines with
4 mil spacing or anything crazy. I did have traces between DIP pads with
no problems.

I didn't realize they were so common and cheap. Wow. This beats the hell
out of trying to modify an ink jet, trust me. The standard pen body can
be used as a holder, just cut off the top, remove the guts, cut off the
tip just at the end of the large taper and slide in an ultra-fine marker.
All you have to be careful of is that you load the pen manually and bypass
the cover interlock switch so you can plot with the flip-up smoked cover
open to clear the tall pen. Set the plot speed to 1IPS, plot a reverse
image and Presto! Nearly instant PCB. Only difficulty might be large
copper areas like ground planes, I seem to recall that doesn't work too
well and will require some manual touching up prior to etching.

*>Maybe there is a GOOD reason why we print to film and then expose?
*>BTW used laser printers (LJIIs & LJIII) can be had for $25 at most
*>computer recycling places. They print gread blacks and are probably
*>quicker from print to etch time than any inkjet direct to PCB kludge.

I agree. But this is a brainstorming discussion and something good may
come of it.

*>And if you are in a larger center you can get photoplots from PDF
*>files at most larger print shops. $10.00 or so for a 8"x10" plot.

That is what I do for more complex deisgns that cannot be prototyped at
home. Unfortunately the printer almost always has 'scale to page' ticked
on his Mac and I have to put a ruler on the sheet and check it. I've had
5% off (it's ok if you have no large parts) and I shut up but with 40 pin
chips you have to be exact.

I've had good luck with this type marker except that it has a large diameter
and is difficult to attach to the plotter pen holder. Ink is very strong -
hard to remove with lacquer thinner after setting a day or so!

Thanks for the info on the red markers. I'm using a hp7475a and Eagle to
layout the boards. Does anyone know how to have Eagle or the MS Windows
plotter driver not pick pen 1 (SP1). Right now I'm sending the plots to a file
and hand editting the pen select out so that the plotter uses the pen I load
manually.

> On Wed, 13 Nov 2002, David Minkler wrote:
>
> > HP 7475A plotters are 'nearly' free (plus
> shipping) on ebay. Search on
> > 7475a.
>
> Ah. Stupid me, I hadn't even looked. Last
> time I did look for one was
> several years ago, and they were hard to find
> then -- but eBay was barely
> a startup at that time. You can do this with
> any of that series of HP
> plotters, I think I also used a 7470 at the
> time.
>
> I can't tell you guys how nice this setup
> works, though. The pens I found
> are only a couple of bucks each, and I could go
> from layout to complete,
> etched & drilled board in about an hour for a
> simple project. Lines were
> very clean, you just have to remember you
> simply can't do 8 mil lines with
> 4 mil spacing or anything crazy. I did have
> traces between DIP pads with
> no problems.
>
> I didn't realize they were so common and cheap.
> Wow. This beats the hell
> out of trying to modify an ink jet, trust me.
> The standard pen body can
> be used as a holder, just cut off the top,
> remove the guts, cut off the
> tip just at the end of the large taper and
> slide in an ultra-fine marker.
> All you have to be careful of is that you load
> the pen manually and bypass
> the cover interlock switch so you can plot with
> the flip-up smoked cover
> open to clear the tall pen. Set the plot speed
> to 1IPS, plot a reverse
> image and Presto! Nearly instant PCB. Only
> difficulty might be large
> copper areas like ground planes, I seem to
> recall that doesn't work too
> well and will require some manual touching up
> prior to etching.
>
> Dale
>
> --
> http://www.piclist.com hint: PICList Posts must
> start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]:
> ->Other [BUY]:,[AD]: ->Ads
>
>
>

About 7 years ago (was it really that long ago?) I had an opportunity to
purchase a number of 7475s for almost nothing. I had them stacked up
like cordwood in my garage until the boss told me to get rid of them
(schools and students). I had planned to make a 'photoplotter' with one
of them. Build an LED/mask/lens insert for a pen body and signal the
LED on from the pen-down solenoid. Write on Kodalith film. Didn't have
blue LEDs back then, red won't work on Kodalith. Project died when I
discovered how inexpensively I could get boards made by houses similar
to APC or Olimex.

There was no (smoked plastic) cover interlock on any of the units I
had. I had several units which had no plastic cover at all (probably
broken and thrown away). It's just a dust cover anyway. There is a
little section of the plastic body which interferes with pens that are
longer than the standard HP pens. This section can be hacksawed out
with no adverse effects. Wouldn't do that on a new $1400 plotter but on
a $30 ebay special ... One of my units came this way. This allowed
the use of the longer HP pens (or the Koh-I-Noor replacements) which are
used in their DraftPro lines.

I only had two units, out of about a dozen, die. One lost a servo drive
transistor. The other had a flakey connection to the keypad. Aside
from that, those were nice little plotters! Thanks for the memories.

>
> Ah. Stupid me, I hadn't even looked. Last time I did look for one was
> several years ago, and they were hard to find then -- but eBay was barely
> a startup at that time. You can do this with any of that series of HP
> plotters, I think I also used a 7470 at the time.
>
> I can't tell you guys how nice this setup works, though. The pens I found
> are only a couple of bucks each, and I could go from layout to complete,
> etched & drilled board in about an hour for a simple project. Lines were
> very clean, you just have to remember you simply can't do 8 mil lines with
> 4 mil spacing or anything crazy. I did have traces between DIP pads with
> no problems.
>
> I didn't realize they were so common and cheap. Wow. This beats the hell
> out of trying to modify an ink jet, trust me. The standard pen body can
> be used as a holder, just cut off the top, remove the guts, cut off the
> tip just at the end of the large taper and slide in an ultra-fine marker.
> All you have to be careful of is that you load the pen manually and bypass
> the cover interlock switch so you can plot with the flip-up smoked cover
> open to clear the tall pen. Set the plot speed to 1IPS, plot a reverse
> image and Presto! Nearly instant PCB. Only difficulty might be large
> copper areas like ground planes, I seem to recall that doesn't work too
> well and will require some manual touching up prior to etching.
>
> Dale
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

*>I think that shellac might be usable, it is organic
*>and non toxic, dissolves totally in alcohol and can
*>be diluted to the right viscosity. I'll buy a
*>paint viscosity measure and some bubblejet refil
*>ink and get a viscosity reading unless someone has
*>more accurate equipment. :o)

You are probably more interested in surface tension and whether exposing
the ink to intense heat leaves any residues on the heater.

*>Someone mentioned the ink used to date code products like soft drink
*>bottles. It certainly is water insoluble, however I was led to believe the
*>stuff is quite poisonous. They had quite a procedure at coca-cola for the
*>refiling and disposing of empty containers.

It's a form of epoxy. It is poisonous before it is cured (by exposure to
air or UV). After curing you can eat it if you like.

*>You should look into the melting temperature of copper with respect to the
*>temperature at which the resin in the fiberglass stops working.

Actually *starts* working. As a conductor ;-)

*>Doesn't sending your boards to Advanced Circuits or PCB Express sound
*>pretty good by now? It's been entertaining watching the each flaky idea
*>trump the next on this thread, but it's getting a bit rediculous now.

Wait, we need to get into ion beam epitaxy before we can finish the
thread.

> > Doesn't sending your boards to Advanced Circuits or PCB Express
sound
> > pretty good by now? It's been entertaining watching the each flaky
idea
> > trump the next on this thread, but it's getting a bit rediculous
now.
>
> My original spec of using special ink in a
> bubblejet followed by etching and SMD hot air
> soldering is not flaky at all.

No, it's genious.

> The only real issue is finding a suitable ink,
> and then the system would be many times cheaper
> and faster than any commercial board house and
> suitable for one-off with tiny PCBs.

Jepp.

> I have discussed the ink issue with my girlfriend
> (who is an industrial chemist) and the problems
> should be simple so solve if anyone gave a damn.

There's the problem!
I'm going to ask a friend of mine... He is fiddling around some university
right now. Head of some chemic thing.
He should have atleast one idea.

> I also checked the ink cartridge in my bubblejet,
> it says "solvent = isopropyl alcohol" so obviously
> the plastic and all mechanisms are alcohol safe.
> This should make it EASY to find a suitable ink
> or lacquer.

I've already pumped some different solutions in mine.
One was a UV-fuorecent oil. (That actually worked out really well btw.)

> Cristian has solved the PCB feed issues or come
> some of the way to solving them.

I have solved it two years ago, when I fisrt saw a straight-paper-path
laser-printer for use with cardboard.
As soon as I'm finished with this little project I'm working on I'll find a
inkjet with same design.

> Thanks BillW, good ideas. Really anything soluble
> in alcohol that dries to a waterproof layer should
> work, as a decent etch resist anyway. Making sure
> it prints well in a bubblejet head and doesn't gum
> up the head when not is use is a fraction harder.
>
> I tested some bubblejet ink on a few surfaces, one
> thing I did note is that it is VERY slow drying,
> and doesn't quite dry at all unless it soaks into
> paper which seems to dry it. I'm guessing this is to
> avoid drying in the head and gunging it up.
>
> I think that shellac might be usable, it is organic
> and non toxic, dissolves totally in alcohol and can
> be diluted to the right viscosity. I'll buy a
> paint viscosity measure and some bubblejet refil
> ink and get a viscosity reading unless someone has
> more accurate equipment. :o)
> -Roman

Problem is you need something without pigments and non-soluable stuff in
it...
Also, it will have to work with the inkjet system.

Coating on inkljet transparancies are simply a protein-membrane.
You can make it yourself with a very clean piece of transparancie and some
eggwhite.
Best result is to thinn the eggwhite just a tad and use a airbrush to apply.

One must not get hung up on a project, instead of a goal. In this case,
the goal is to produce PCBs faster and cheaper than a commercial board
house, and we're specifically looking at inkjet printers because:

Potential advantages of Inkjet printers for PCB fabrication
-----------------------------------------------------------
1) Inkjets are cheap, widely available, and widely supported.
2) Inkjets are good (relatively speaking) at "filling in" large print areas.
3) Inkjets are fast, printing a full 8x10 page in a couple of minutes, even
with large filled areas.
4) Inkjet mechanics are relatively simple and potentially easy to modify.
5) Ink cartridges are potentially refillable with all manner of exotic
concoctions.
5) "instant" output.

On the flip side, you also need to remember the disadvantages of this
scheme, compared to a commercial board house:

Disadvanatges of inkjet technology:
1) inkjet cartridges are typically rather expensive.
2) inks modifed for PCB resist may be hard on inkjet mechanisms (clogging,
solvent efect on plastic parts, etc.)
3) (consumer) inkjet technogy is designed for absorbent media.
4) The further you move from off-the-shelf inkjet technology, the less
desirable the option looks. You don't want to have to prepare special
ink, clean your ink paths, coat your board with an absorbant or
chemically active layer, etc, etc for each board you "print."
5) printing chemical resist direct to the PCB only eliminates a couple of
the steps in typical home PCB fabrication (photocoat, expose, develop),
and they're not the most obnoxious steps. You still need to etch and
drill, for instance.

(hmm. Here's another idea. The typical commercial board maker seems to use
a photoresist that goes away where tracks are desired, then tin plates, then
removes all photoreists and etches using the tin plate as resist. This
raises the possibility of using something like an electroless tin plate
solution in your inkjet cartridge - it doesn't NEED to dry anymore, just so
long as it deposits enough tin before being washed.)

>I had excellent luck using a .5mm permanent marker that
>I found at an art store. I had a cut-down HP felt tip
>plotter pen body that the new marker friction-fit into.
>By setting the plot speed down to 1 or 2 inches per second,
>I got near perfect boards every time. I was only making
>single sided boards, but I suppose with enough work one could
>probably get a double sided board done the same way.

I had heard of this being done as well, and have been meaning to try it for
some time. Will mean I will be able to get some projects done too :)))

>I had to tape the PCB to a sheet of paper because the
>registration process was at high speed regardless of
>the plot speed you had set, and the rollers didn't grip
>the PCB material well enough to prevent slipping under
>that kind of acceleration.

I had wondered about this. Good to see it confirmed.

>The pen was a common ultra-fine permanent ink pen,
>available in several colors from the local art supply joint.....

>Does anyone know how to have Eagle or the MS Windows
>plotter driver not pick pen 1 (SP1). Right now I'm
>sending the plots to a file and hand editting the pen
>select out so that the plotter uses the pen I load
>manually.

What happens if you take all the other pens out of the plotter? IIRC the
plotter will use whatever pen it finds first if there is no pen in the
requested slot.

>I only had two units, out of about a dozen, die. One
>lost a servo drive transistor. The other had a flakey
>connection to the keypad.

The one I got for free was one of a pair the company I worked for at the
time had. This one died, and one of the engineers had identified the bad
chip in it by swapping pluggable chips between the two machines. They were
going to throw it out, as HP (New Zealand) would not sell them the chip, but
required the plotter sent to them to be sent to the USA for repair, cost
something like NZ$900. (about US$450) !!! Hence it was rubbish min material,
so I said throw it my way. I went investigating the chip with the HP special
number on the top, and low and behold, on the bottom it said 6802. Having
some other gear with 6802 CPU's in them, I grabbed a chip on the off chance
that it was a standard CPU chip, and low and behold the printer now worked
:))) Went fishing for a manual for it, and our supplies department sourced
one for me for $20. I figured I had a pretty good deal.

Once you mount a full size pen on the plotter arm it doesn't fit through the
slot to get to the pen carousel to see that there are no pens to load.

I had hot glued a spring clamp to the back side of the arm since the pens I'm
using are too large to fit into the standard pen hold. I'm not sure the
plotter arm is smart enough to know if it has a pen already loaded in it?

> >Does anyone know how to have Eagle or the MS
> Windows
> >plotter driver not pick pen 1 (SP1). Right now
> I'm
> >sending the plots to a file and hand editting
> the pen
> >select out so that the plotter uses the pen I
> load
> >manually.
>
> What happens if you take all the other pens out
> of the plotter? IIRC the
> plotter will use whatever pen it finds first if
> there is no pen in the
> requested slot.
>
> --
> http://www.piclist.com hint: The list server
> can filter out subtopics
> (like ads or off topics) for you. See
> http://www.piclist.com/#topics
>
>
>

You might be able to design your pcb
own printer completely see link below.

Has anyone tried one of the techtronix phaser or xerox color or b&w
wax printers ?

Usually find one or two in somewhere like quick copy
or kinkos etc

does the wax work better than ink ?

I've spilt water on pictures(on A4 paper) printed by a wax printer and it
makes them reasonably water resistant

Al

university.xilinx.com/products/xaw/prt/prt_ap1.htm
Using Xilinx Programmable Logic with High Speed Printers
Introduction
The underlying goal of this document is to introduce designers to the value
that Xilinx Programmable Logic can provide to the world of printers. The
approach we will take here is to basically build up the functionality needed
to make a mainstream ink jet printer, so the required functionality is
identified, and the performance improvement is understood for each
refinement. At the end of the process, we will outline a more ambitious
solution by embedding our work into the framework of MultiFunction
Peripherals, a rapidly emerging market frontier.

> You might be able to design your pcb
> own printer completely see link below.
> Has anyone tried one of the techtronix phaser or xerox color or b&w
> wax printers ?
> Usually find one or two in somewhere like quick copy
> or kinkos etc

Oh, yeah!!!
They will be sooooo happy when I march in there and stuff a 100x170x1.2mm
PCB in one of their printers :-)
It was a fun idea while it lasted...

> does the wax work better than ink ?

If you could get the wax onto the pcb it would probably work great as long
as the temps on the etching was kept to a bearable simmer.

> I've spilt water on pictures(on A4 paper) printed by a wax printer and it
> makes them reasonably water resistant

You CAN get VERY thin PCB material (what do you think they laminate
together to make those 12-layer boards!) Not all that much less flexible
than card stock (though it's a lot harder, of course.)

In fact, I remember there was one would-be competitor for the LPKF/T-tech
style mechanical etchers that used thin stock wrapped around a drum to
simplify their mechanics. You were supposed to then mount the thin PCB
material onto a thicker substrate. It seemed a bit weird at the time ("aha!
they want to lock you into buying THEIR PCB materials!"), and I only saw
them once (a long time ago.)

The very thin stuff seems to be about as common as single sided PCB material
at the local surplus stores (there, but not very common), so perhaps a
scheme that was limitted to such special material might be useful...

>I'm not sure the plotter arm is smart enough to know
>if it has a pen already loaded in it?

Well the arm isn't :)

But on my HP7475 it goes through various motions at times to try and grab a
pen from the carousel, or put one in it. I suspect it measures arm position
and motor current to determine the relative states of arm/carousel empty or
occupied. The arm and carousel certainly do a little dance together at
various times as pen requests occur.

I've also used PCB-Pool about half a dozen times for prototypes - no
complaints whatsoever on quality- on the one occasion they were a
couple of days late they shipped by next-day courier at no extra cost.

They're probably not the cheapest for production runs but for 1-5 off
prototypes I've yet to find better due to lack of tooling costs.

On Wed, 13 Nov 2002 10:54:41 -0000, you wrote:

>I have never had any problems with them. Have used them at least half a
>dozen times for plated through hole one-off boards. They delivered when
>they said they would at the price they quoted. No problems with the
>quality. Only hassle is the silly file format they require.

They now accept a large number of formats, including Gerber.
Eagle,Ultiboard, Target, Protel,Orcad, Quickroute and Proteus

Personally, I never had a problem with sending them GC-Prevue .gwk
files - it's a useful format that includes all info in a single file,
and putting your gerbers through GC-Prevue takes only a few seconds,
and gives an extra check that the files are correct.

>Has anyone tried one of the techtronix phaser or
>xerox color or b&w wax printers ?

>Usually find one or two in somewhere like quick copy
>or kinkos etc

>does the wax work better than ink ?

My colleagues have used a Tek Phasor to print onto a transparency to light
expose resist. The wax used in the printer seems to make a better master for
doing this as it is much denser than toner in a laser printer on
transparency. I have heard of people using these to make silk screens as
well.

You must remember to use transparencies designed for the Phasor though,
otherwise you end up with an expensive mess inside the printer :)))))

It all depends on the arm. My CalComp 2024 knows it has a pen by the
thickness.
In other words:
- if it can close it's claw, there is no pen.
- if it can close it just right, there is a pen!
- if it can't close it enough, there is a malfunction!

>It all depends on the arm. My CalComp 2024 knows
>it has a pen by the thickness.

OK so the calcomp has an active clamp on the arm, but all the HP plotters I
have seen just clip the pen into the arm using the force of the motor to
drive the arm into the pen in the carousel. Hence the way I described that
software "plays games" to find out if there is a pen in the arm.

Kyrre Aalerud wrote:
>
> I just did this with a CalComp 2024 8 pen plotter.
> I used a CD-marker (0.7mm) as a pen.
>
> It worked, but I see I need better coverage/adhesion so the print won't
> loosen under etching.
>
> The cool part is that I use Eagle CAD and just set the CAM Processor for
> HPGL and output to com1 :-)
> I work under Windows 2000 by the way !!!

I just got back to the list and saw all the PCB
posts, gee this seems to be a popular thread
anyway. :o)

Obviously a flatbed plotter will do waterproof
ink (etch resist) direct to PCB and people have
been doing this for years. BUT this is slow and
has problems with tip wear and damage if/when
running off the edge of the PCB.

And using a non-flatbed plotter raises all the
same feed problems as using a bubblejet, with none
of the bubblejet advantages.
-Roman

Dal Wheeler wrote:
>
> When I played with this kind of thing on an old HP plotter, the recommended
> resist pen ink was a staedler red felt marker. I replaced the felt soaked
> core of the standard plotter pens with a scavanged staedler pen. You can
> get a bottle of the same ink (although it's special order around here.).
> Might try to see if it will work in an ink jet nozzle.

Just about any waterproof marker will work as
an etch resist, as long as the coating is
thick enough. I've even used the waterproof felt
tips sold in supermarkets.

To get the ink to a decent thickness you need to
ensure the pen traverse is slow enough, meaning
the plotter speed has to be run on slow which is
exascerbating the problem with the plotter solution.
There is also a slight tendency for the tip to
"scrub off" ink from previous passes, making it
harder to do large inked areas, which is one
area (pun?) that the bubblejet will really outperform
the plotter. :o)
-Roman

Most of the SMD parts are becoming cheaper than
the through-hole parts these days, are much smaller
and remove a lot of the assembly time and costs.

Where Olin has been harsh about beginners learning
the new technology PICs etc, *maybe* they should be
learning the new technology in hobby construction
too? Maybe every beginner should have a little
hot-air gun next to their soldering iron??
Just a thought. :o)
-Roman

> To get the ink to a decent thickness you need to
> ensure the pen traverse is slow enough, meaning
> the plotter speed has to be run on slow which is
> exascerbating the problem with the plotter solution.
> There is also a slight tendency for the tip to
> "scrub off" ink from previous passes, making it
> harder to do large inked areas, which is one
> area (pun?) that the bubblejet will really outperform
> the plotter. :o)

Assuming anyone actually gets a bubblejet working. Plotters are known to
work. But if anyone can get a bubblejet squirting resist ink, I'm sure
it's you.

As an aside, I was looking at the homemade hot air tool discussed on the
list a while back. Pictures at http://www.usbmicro.com/apps/ . I bought
the desoldering tool, but I have yet to get a pump. Has anyone made one
of these and used it? Any advice on pumps? I'd imagine if the pump blows
too quickly the air won't have enough time to heat up.

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
-Douglas Adams

Roman Black wrote:
> too? Maybe every beginner should have a little
> hot-air gun next to their soldering iron??
> Just a thought. :o)

*>Kyrre Aalerud wrote:
*>
*>> I've already pumped some different solutions in mine.
*>> One was a UV-fuorecent oil. (That actually worked out really well btw.)
*>
*>
*>Excellent! So if an oil pumps ok in a bubblejet
*>head we can assume most liquids will. I had already
*>guessed alchohol would with a boiling point less
*>than water, but oil is good news!
*>
*>Peter's point about crub being baked inside the
*>head is valid though, this could be the biggest
*>problem with bubblejet.

Actually the biggest problem with bubblejet is splatter. Print a sheer
black line on a sheet of paper (make sure it is not aliased - it should
have a jagged appearance if not vertical or horizontal) and take a 5x or
more loupe and look at it. Repeat with pcb film and laser printed
transparency.

> > I've already pumped some different solutions in mine.
> > One was a UV-fuorecent oil. (That actually worked out really well btw.)
>
> Excellent! So if an oil pumps ok in a bubblejet
> head we can assume most liquids will. I had already
> guessed alchohol would with a boiling point less
> than water, but oil is good news!
>
> Peter's point about crub being baked inside the
> head is valid though, this could be the biggest
> problem with bubblejet.

This already IS the biggest problem with a inkjet/bubblejet. That is why
they are now using a rubber-gasket that they hide the head in when not in
use. Some models actually squirt some ink into it each time they land...
To keep it moist. Then they seal off. Each time you turn the printer on,
it goes through a head cleanup to remove any leftovers from sitting in the
gasket.

Maybe we need a two part chemical. Something we can print with the
bubblejet, that won't cure without a hardener. --Something like epoxy, but
w/o the mess. --I can't ever seem to get the bottle lid screwed tight
enough to keep the epoxy in let alone trying it in a inkjet cartridge!
Something that will polymerize an oil based substance?
{Original Message removed}

> Maybe we need a two part chemical. Something we can print with the
> bubblejet, that won't cure without a hardener. --Something like epoxy,
but
> w/o the mess. --I can't ever seem to get the bottle lid screwed tight
> enough to keep the epoxy in let alone trying it in a inkjet cartridge!
> Something that will polymerize an oil based substance?
> ----- Original Message -----
> From: "Kyrre Aalerud" <RemoveMEkreatureRemoveMEEraseMEC2I.NET>
> > > Peter's point about crub being baked inside the
> > > head is valid though, this could be the biggest
> > > problem with bubblejet.
> >
> > This already IS the biggest problem with a inkjet/bubblejet. That is
why
> > they are now using a rubber-gasket that they hide the head in when not
in
> > use. Some models actually squirt some ink into it each time they
land...
> > To keep it moist. Then they seal off. Each time you turn the printer
on,
> > it goes through a head cleanup to remove any leftovers from sitting in
the
> > gasket.
>
> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> email KILLspamlistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body
>
>
>

> ----- Original Message -----
> From: "Dal Wheeler" <KILLspamdwheelerspamBeGoneINSIGHTEK.NET>
> > Maybe we need a two part chemical. Something we can print with the
> > bubblejet, that won't cure without a hardener. --Something like epoxy,

Urea/formalahyde resins have water-soluble constituants that react and
polymerize to form a non-water-soluble "plastic." I don't know whether
it's non-porous enough to serve as resist. I also don't know whether it
can be stripped easilly. And formalahyde is reasonably nasty stuff.

I have never tried (not even looked at) SMD placement. What is the essential equipment for a beginner to have to start SMD placement. If it is just the list below, I just need the solder paste syringe to get me going. How hot must the hot air gun be at when soldering?

Interesting, but Radio Shack sells a squeeze-buld desoldering iron that
might be easier to adapt. Cat. #64-2060, $9.99, 45W. It's available with
interchangeable tips with holes of different sizes, and a second tube for
the sucker. One could probably pretty easily attach a low-volume air source
to that. Just an idea.

A pair of tweezers, preferably the sort with "normally closed" jaws, rather
than the "normally open" type commonly available. The "normally closed" type
allow you to hold components without having to think about keeping the
tweezers closed. If you use the "normally open" type, then the effort of
holding the component with just the right amount of pressure leads to a
situation where it is all to easy to twist the jaws sending the component
flying to where you will never find it :)

A good magnifier, my preference is a headband stereo magnifier of about
2.5x, an Optivisor or similar. If dealing with extremely tiny components you
may wish to get a higher magnification, but I find the larger magnifications
harder to use.

I must say that I disagree with you about the solder and a very fine tip.
I saw a demonstration in HAKKO (solders manufacturer) and they use/sell a
small special soldering paste that you put on the smd ic pins and then you
can use *ANY* solder (15W-40W) and just put the solder tin on *ALL* pins. I
was in shock cause I thought all the pins will be soldered together!
but like in magic it didn't happened. this small tube solved my smd
soldering problems.
and it's not too expensive either.
Regards

I do this with normal solder and a 1.5mm tip using a 35w iron. (No, I'm not
talking golf!)

I simply solder along the side of the chip. (Often SO18 of 16F84 or 628
PIC's)
Soldering on all legs in a single controlled stroke while feeding solder
very slowly.
This technique has taken me some time to master, but it makes soldering of
theese packages simple without any special tools.

For small prototyping I solder components down to 0402 with a pair of
tweezers and the same 1.5m m tipped 35w iron. After all, they're not that
small? They are actually 1 mm long, and that's plenty!

I will admit that I am still young and that I will definately not be able to
keep this up as I age, but for now it woks. Shaking hands may come sooner
than one expects when dealing with such small scales :-)

I do have a gas torch that have a hot-air muzzle but I can't use it for
continous operation as it turns out the tip get's too hot and the tool
starts to melt!!! And this is a quality instrument from Rothenberger...

> Alan
>
> I must say that I disagree with you about the solder and a very fine tip.
> I saw a demonstration in HAKKO (solders manufacturer) and they use/sell a
> small special soldering paste that you put on the smd ic pins and then
you{Quote hidden}

> can use *ANY* solder (15W-40W) and just put the solder tin on *ALL* pins.
I
> was in shock cause I thought all the pins will be soldered together!
> but like in magic it didn't happened. this small tube solved my smd
> soldering problems.
> and it's not too expensive either.
> Regards
>
> Tal Bejerano
> AMC - ISRAEL
>
>

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
-Douglas Adams

Dale Botkin wrote:
> Interesting, but Radio Shack sells a squeeze-buld desoldering iron that
> might be easier to adapt. Cat. #64-2060, $9.99, 45W. It's available with
> interchangeable tips with holes of different sizes, and a second tube for
> the sucker. One could probably pretty easily attach a low-volume air source
> to that. Just an idea.

I thought we has just about finished with this topic, but I had a new
thought... Even if we (by which I mean Roman :-) are unable to find
an ink that works as etchant resist, there might still be usefulness
from inkjets for print soldermasks and/or "silkscreen" layers on PCBs.
Both of these have less stringent requirements of the ink (both in
resolution and chemical resistance) AND (unlike etching) they're tasks
with fewer alternatives for the amateur...

> ----- Original Message -----
> From: "Kyrre Aalerud" <kreaturespam_OUT@spam@C2I.NET>
> To: <.....PICLISTspam.....MITVMA.MIT.EDU>
> Sent: Saturday, November 09, 2002 7:08 PM
> Subject: Re: [EE]: Printer to PCB?
>
> > Now there's an idea!!!
> >
> > You need to find out what ammount of UV you need and then what
> source to
> > use.
> > Then, just make a plotter-jig with X/Y movement and some defined
> pitch.
> >
> > This could be really cool. Too bad normal laser-pens atre way too
> low
> > wattage.
> > You would need an hour on each point of more!
> >
> > Kyrre
> Just a thought on the subject.. I may be very wrong.
> As I recall, laser light is a VERY specific wavelength, not the usual
> mix of assorted wavelengths that we perceive as white.
> If the photosensitive material needs to be exposed by UV, I would
> think that an off-the-shelf red laser pointer might never expose the
> surface at all.
>
> I like the idea though. It could offer great precision without
> excessive wear on the printer parts.
>
> If my beliefs regarding laser light are incorrect, I'm sure some
> better educated person will point this out.

Again, sorry for the late reply.

Would it be possible to put a thin layer of a liquid etch/photo resist
all over the board (perhaps submerge it in a bed of liquid that just
barely covers the board) and use a laser (or bright focused light
source) to dry or cure the resist where the traces are? Then remove the
board from the bath and the liquid runs off leaving dried resist on the
board. The light source could be scanned across the board like a print
head to create the necessary pattern.

Does anybody remember the old rapid prototyping machines that used a UV
laser to cure a model out of a pool of polyethylene? Hmmm...now that I
think of it, the modern RPM's are basically 3D inkjets. I wonder if they
can print conductive polymer.

Josh Koffman wrote:
>
> Perhaps if we could get a device that could emit a focused beam of
> energy at the resonant frequency of copper...

Ultrasonics? The resonant frequency would be based on the thickness of
the copper, its stiffness, adhesion to the substrate and the stiffness
of the substrate. Although, it should be possible to tune the freq on
the fly by observing the reaction of the board. Or maybe find a common
center frequency and then xmit a bunch of freqs around it. Focusing the
sound would be difficult, but if the transducer is close enough to the
board it shouldn't be a problem.

>Josh Koffman wrote:
>
>
>>Perhaps if we could get a device that could emit a focused beam of
>>energy at the resonant frequency of copper...
>>
>>
>
>Ultrasonics? The resonant frequency would be based on the thickness of
>the copper, its stiffness, adhesion to the substrate and the stiffness
>of the substrate. Although, it should be possible to tune the freq on
>the fly by observing the reaction of the board. Or maybe find a common
>center frequency and then xmit a bunch of freqs around it. Focusing the
>sound would be difficult, but if the transducer is close enough to the
>board it shouldn't be a problem.
>
>
He might have been referring to the resonant frequency of the copper
atom, rather than a structure, much like the microwave oven is tuned to
water's frequency.

>
> Brandon Fosdick wrote:
>
> >Josh Koffman wrote:
> >
> >
> >>Perhaps if we could get a device that could emit a focused beam of
> >>energy at the resonant frequency of copper...
> >>
> >>
> >
> >Ultrasonics? The resonant frequency would be based on the thickness of
> >the copper, its stiffness, adhesion to the substrate and the stiffness
> >of the substrate. Although, it should be possible to tune the freq on
> >the fly by observing the reaction of the board. Or maybe find a common
> >center frequency and then xmit a bunch of freqs around it. Focusing the
> >sound would be difficult, but if the transducer is close enough to the
> >board it shouldn't be a problem.
> >
> >
> He might have been referring to the resonant frequency of the copper
> atom, rather than a structure, much like the microwave oven is tuned to
> water's frequency.

I should have been clearer. I was trying to suggest ultrasonics as an
alternative to an EM solution. It would probably be easier and such a device
might be able to switch between cutting copper and cutting fiberglass just by
changing frequencies.

> > >Ultrasonics? The resonant frequency would be based on the thickness of
> > >the copper, its stiffness, adhesion to the substrate

> I should have been clearer. I was trying to suggest ultrasonics as an
> alternative to an EM solution. It would probably be easier and such a device
> might be able to switch between cutting copper and cutting fiberglass just by
> changing frequencies.

What about an EDM machine? PCB laid flat with electrolyte
on top, a suitable electrode on top passing over the PCB
and EDM'ing the copper away. Some attention needed to the
tool path to maintain a conductive copper PCB path to the
last moment, but that's not hard. This would be a clean,
quiet and *very reliable* way of removeing copper from
a PCB. :o)
-Roman